Thanks for digging that up. Is he worth a multi year contract for at least $25 mil a year? That seems to be superstar range and I'm not sure that Rendon qualifies as such.
I think Rendon's production, particularly this year, qualifies him as a superstar (contract year uptick, always the same).
I suspect the Nats will have to pay a premium to keep him. This is based on gut feeling (and is discussed above) that he really wants to be in Texas; Houston ideally though they are extremely unlikely to be able to afford him and find him a position to play.
The other gut feeling about Rendon (again, well discussed on this board) is that he doesn't "love" baseball. I'm not saying he doesn't take his job extremely seriously but it is, at the end of the day, a job. Not loving the sport might make contract negotiations a little different from the norm. However, having said all that, with Boras has his agent, he's likely going to the highest bidder!
Age is the other thing - it's not unusual for players to be Rendon's age when they hit FA and generally those contracts are becoming less and less absurd as GMs finally realise that production drops off considerably more than it used to as players move towards their mid 30s. Whether Tony's do or not is the multimillion dollar question. Looking at his physique and mechanics he'll be worth taking the risk on for multiple GMs and as a result will get that sort of money and I reckon I want the Nats to be in on him, even if it's futile as I think it probably will be.